[Meta] Prioritize IE11 & Edge testing same as regular browser testing for features and bug fixes that we ship

Background

We have several critical functionalities broken in IE11 & Edge web browsers, either due to velocity of development or due to missed testing. See gitlab-ce#29732, gitlab-ce#29742, gitlab-ce#29747 and gitlab-ce#25788 for instance.

Along with our large community, GitLab is aiming at enterprises with EE, and those enterprises are largely on Windows running IE as primary browser (with very restrictive IT policies), although majority of our users include small development teams to large software development firms (which presumably includes tech savvy users) who may not be using older web browsers, but our documentation does suggest that we support Microsoft Edge and Internet Explorer 11.

Proposal

Approach

We ensure every feature/fix that is no longer a WIP and is ready for review is also tested in all web browsers (as mentioned in GitLab Supported Web Browsers) and not just the one we use, until this gets automated in CI.

Identify Issues

I have created two labels ~"Internet Explorer" and ~"Microsoft Edge" which can be used to mark issues that affect either of the browsers.

Signing Off Merge Requests

I have created a label ~"All Browsers Compatible"; developers ensure that this label is added to MR before assigning to any endboss for review, endbosses ensure vice versa.

Exceptions

Obviously, there will be situations where we have a highlight feature ready to ship which isn't fully functional in IE & Edge, but we don't hold them until they're available in those browsers but we make sure that the limitation is tracked and is properly communicated to our users as a part of release notes. This will help us fix those limitations in upcoming releases and prevent known issues from being reported.

If we agree to proceed with this proposal, I'll add information about this process to Frontend Development Guidelines documentation. Suggestions and feedback is most welcome. ♥